TERRAFORMING TERRA
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A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.

Saturday, August 27, 2011

From Worm to Man

The take home is that our kidneys
evolved long before life split into vertebras and moulters.It also means that work on flatworms will led
to direct regeneration of some organs ate least.Recall the liver does so anyway.Thus extending that capability for some organs
at least seems appears plausible.

Replacing organs naturally or
artificially are both emerging protocols that we will soon be seeing a lot more
about.It is surely happening.

I would like to see medical
research literally throw away the regulatory governors for one decade.We now know vastly more about fundamental
processes so that we can hugely control any damage although losses will
occur.It will still payback in lives
saved.

Our bodies are perfectly capable of renewing billions of cells every
day but fail miserably when it comes to replacing damaged organs such as kidneys.
Using the flatworm Schmidtea mediterranea-famous for its capacity to regrow
complete animals from minuscule flecks of tissue-as an eloquent example,
researchers at the Stowers Institute for Medical Research demonstrated how our
distant evolutionary cousins regenerate their excretory systems from scratch.

In the process, the Stowers team led by Howard Hughes Medical Institute
and Stowers investigator Alejandro Sanchez Alvarado, Ph.D., not only
established flatworms as a valuable model system to study tissue maintenance
and organ regeneration but also provided new clues about the evolutionary
origin of mammalian kidneys. Their study is published in the current issue of
the journal Development.

"The past ten years of planaria research have shown that
planarians use pretty much the same molecular toolkit for building their bodies
as other animals," says first author Jochen Rink, Ph.D., formerly a
postdoctoral researcher in the Sanchez lab and now a group leader at the
Max-Planck-Institute of Molecular Cell Biology and Genetics in Dresden,
Germany.

"Because of this fundamental similarity between all animals,
understanding how a worm assembles its excretory system may very well be
relevant to understanding kidney physiology and regeneration in humans,"
he adds.

Most animals studied in the lab fall within two main branches on the
evolutionary tree of life: mice, rats, and salamanders are part of the
vertebrate lineage, while fruit flies and the roundworm Ceanorhabditis elegans
belong to the lineage encompassing molting animals.

"People have drawn conclusions about the evolution of certain
attributes by looking exclusively at these two branches," says Sanchez
Alvarado. "That's akin to trying to work out your family tree but ignoring
your entire maternal lineage."

In contrast, flatworms, also known as planaria, are part of a branch
that has been largely ignored by modern molecular biology. "The so called
lophotrochozoa are an incredibly large and diverse group of animals we know
very little about," explains Sanchez Alvarado.

What was known is that-unlike fruit flies and C. elegans-planaria
possess very complex excretory systems akin in many respects to mammalian
kidneys. "Planarian protonephridia are so far the only invertebrate model
system that combines pressure filtration with filtrate modification similar to
mammalian nephrons, the basic functional unit of the kidney," explains
Rink. Their anatomy, however, was not well understood.

When Rink and co-first author Hanh Thi-Kim Vu, Ph.D., a graduate
student in the Sanchez Alvarado lab, analyzed their structure with the help of
electron microscopy, the scientists found that planarian protonephridia are
complex epithelial organs that organized in a consistent and hierarchical
manner: a distal tubule branching out into proximal tubules, each of which is
topped by a ciliated flame cell-so named because under a microscope the beating
of the cilia resembles a flickering candle.

But more importantly, they noticed that the endothelia forming the
tubules are composed of a fixed succession of different cell types along their
length reminiscent of the mammalian condition. "This suggests to us
that the mammalian kidney originated before the branches split," says
Sanchez Alvarado. "The homologous structures in fruit flies and C. elegans
diversified and diverged till they no longer resembled their common
ancestor."

Protonephridia are distributed throughout a flatworm's body. To study
their development researchers could simply cut the animals' heads off and watch
how they regrew the missing body part including excretory tubules within a
week. They found that protonephridial tubules originated from a precursor
structure, which undergoes extensive branching morphogenesis, the same process
that also shapes vertebrate organs such as lung, kidneys or mammary glands.

When Rink interfered with the expression of EGFR5, short for epidermal
growth factor receptor, during the regeneration process protonephridia could no
longer undergo branching morphogenesis.

If he did the same in non-regenerating planaria, they were unable to
maintain the structural integrity of their protonephridia, which told him that
under normal conditions the organ is constantly maintained through cell
renewal.

"We take it for granted that we go to bed with two sets of
fully functional kidneys and that we wake up with them the next morning but we
don't understand the fundamental processes that give rise to this very well
choreographed maintenance of an organism's form and function," says
Sanchez Alvarado. "We can now start to use planaria as a model to begin to
understand how an adult animals maintain their form and function over a very
long time."

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Apr 2017 - 4.1 Mil Pg Views, March 2013 - Posted my paper introducing CLOUD COSMOLOGY & NEUTRAL NEUTRINO rigorously described as the SPACE TIME PENDULUM, September 2010 I am pleased to report that my essay titled A NEW METRIC WITH APPLICATIONS TO PHYSICS AND SOLVING CERTAIN HIGHER ORDERED DIFFERENTIAL EQUATIONS' has been published in Physics Essays(AIP) and appeared in their June 2010 quarterly. 40 years ago I took an honors degree in applied mathematics from the University of Waterloo. My interest was Relativity and my last year there saw me complete a 900 level course under Hanno Rund on his work in relativity,as well as differential geometry(pure math) and of course analysis. I continued researching new ideas and knowledge since that time and I have prepared a book for publication titled Paradigms Shift&. I maintain my blog as a day book and research tool to retain data and record impressions and interpretations on material read. Do join my blog and receive Four items of interest daily Monday through Saturday.